1. Field of the Invention
The invention relates to computerized controls for printing machines and methods for setting up printing operations.
2. Background Art
Data for controlling the printing process are supplied to the press from a very wide variety of sources. The processing and updating of these data call for considerable labor on the part of the press operator and any supporting staff. Also, the associated data job procedure and the overhead involved call for optimal execution at the printing press. It is only at the press that the data necessary for dealing with a client's job converge and where in the event of delay the major financial loss occurs. The printing press has the highest hourly rate in the chain involved in dealing with a job.
A conventional control and method scans the proof sheet or a printed sheet for measurement in order to derive presetting values for the zonal ink metering elements. Preferably, such a system uses a central microcomputer along with additional microcomputers for scanning of the sheet and adjusting the zonal ink metering elements, as is described in Schramm et al., U.S. Pat. No. 4,200,932 issued April 29, 1980.
Sensing using film originals is unsatisfactory because it is too inaccurate.
Measuring methods are also known which, with the use of one or more sensors, measure a plate lying flat on a table or a plate made ready on a cylinder, in both cases outside the press. See, for example, Sugawara et al. U.S. Pat. No. 4,233,663 issued Nov. 11, 1980, and Murray et al. U.S. Pat. No. 3,958,509 issued May 25, 1976. The measured surface coverage values are transmitted between data stores or memories and, in a further working step, the values are conveyed to adjusting devices for the zonal ink metering elements.
All these methods are relatively complicated and lack data for job control resulting in a relatively unreliable overall system. The resulting accuracy of preadjustment is therefore not very high.
French Patent No. 1,519,883 published Apr. 14, 1968 discloses a plate cylinder for a rotary offset press, the cylinder having provision for zonewise scanning of plate inking, inking being sensed in the various ink zones by means of a densitometric measuring device over the whole periphery of the plate cylinder as the cylinder rotates.
Greiner U.S. Pat. No. 4,437,403 issued Mar. 20, 1984, discloses an automatic control method and apparatus for adjusting the register of printing plates by scanning register marks on the plates when the plates are mounted on their respective plate cylinders.
West German Patent No. 2,922,964 published Dec. 20, 1979 discloses a system for making ready and controlling a printing press; the presetting or preadjustment concerns mainly the inking unit, moisture conveyance and the damping and folding unit. The aim is said to be to provide a system enabling these mechanical parts of a press to be preadjusted and further adjusted automatically. To this end, the invention provides inter alia means for predetermining the necessary mechanical adjustments in dependence upon input data. Parameters such as the printing press, the printed product, the printing zone and the job procedure can be introduced for preadjustment.